The present invention relates to data processing or computer systems and more particularly to interrupt apparatus associated with such data processing systems.
In data processing systems, interrupt facilities are required in order to acknowledge and thereafter service external events which occur during the normal course of operation of the computer system. Although the computer system is executing various operations under computer program control, nevertheless, depending upon the type of interrupt, such interrupt must be handled in an expeditious manner. Such interrupts such as that of the power failure type must be serviced immediately so as to enable the storage of, for example, the status of the system at the time of the power failure. On the other hand it is important that at certain times, such interrupts be suppressed so that certain functions in process may be carried out. For example, if interrupt service is being provided for a particular interrupt type, this should not be interrupted by yet a further interrupt. Depending upon the type of interrupt, it is often desirable to suppress such interrupt for one or more instruction times in order to, for example, enable the completion of a particular operation which may take one or more instructions to complete or to enable each operation to get started, Thus, it is important to give priority to the interrupt types and provide service for the highest priority active interrupt unless for other reasons, the interrupt must be suppressed for a given period of time.
It is accordingly an object of the present invention to provide improved interrupt apparatus for use in a data processing system, such interrupt apparatus having unique suppression capabilities.